The Cambodian government has threatened to expel a United Nations envoy, accusing him of "unacceptable interference" in the country.

The warning came after the UN called for "a transparent and participatory" process as parliament debated an anti-corruption law.

Human rights and opposition groups say the law is deeply flawed.

Monitoring groups routinely list Cambodia as one of the most corrupt countries in Asia.

In the latest spat, Foreign Minister Hor Namhong sent a letter to the UN resident coordinator, Douglas Broderick, complaining about what he called "flagrant and unacceptable interference in the internal affairs of Cambodia".

This was a reference to a statement released by the UN on 10 March, just before the anti-corruption law was passed by parliament, calling for more public discussion.

Mr Broderick had noted that "no draft law has been shared with interested stakeholders, including civil society, since 2006".